Protect and clean PDFs

Protect a PDF with a password, unlock a file you own, redact selected areas, edit metadata or flatten forms and annotations.

5 tools

Match the protection step to the information you are protecting

Reviewed . How we check our guidance

Password protection, metadata cleanup, flattening and redaction solve different problems. A document can be password-protected while still containing a hidden name, or look redacted while covered text remains extractable. Choose the operation from the information that must remain or be removed.

Choose between nearby tools

Control opening or remove a password you know?

Protect PDF creates an encrypted copy with the supplied passwords and permission settings. Unlock PDF creates an unencrypted copy when you provide a valid password and are authorised to do so. Viewer permission flags are not a guarantee against every form of copying.

Remove sensitive page content or just add a mark?

The redaction workflow replaces selected areas with black pixels and rebuilds every page as an image. Text, links and interactive fields are lost even on unmarked pages. A watermark, crop, text overlay or blur is not an equivalent removal step; review all other occurrences of the sensitive information too.

Clear standard properties or make a fixed visual copy?

Edit PDF metadata changes the supported document properties; it is not a complete hidden-data sanitiser. Flatten PDF produces a rasterised visual copy rather than simply locking fields, so selectable text and interactive features are lost.

Prepare a limited-disclosure copy for an intended recipient

Work from a duplicate and list the specific information the recipient should not receive. Include repeated headers, appendices and properties, not just the first visible occurrence.

  1. Remove the selected page areas

    Follow the tool’s redaction method and inspect every selected area. Check that required neighbouring text remains readable and all repeated occurrences have been addressed.

  2. Review supported document properties

    Inspect title, author and other supported fields in the redacted copy. Clear or replace inappropriate values, then reopen the export to check them.

  3. Protect the reviewed sharing copy

    If opening should require a password, use a private password and test the download with both correct and incorrect input. Give the recipient the password through an appropriate separate channel.

Each stage creates another local copy. Keep the original secured and share only the reviewed final file. Password protection does not remove information and should not substitute for the earlier review.

Check the output before using it

  • Open the exact file you intend to share, not a stale preview. Check all pages visually and examine relevant properties and text extraction results.
  • Failure to find a secret with text search is not enough by itself: an image can still display it. Review both the visible pages and the operation’s stated limits.
  • Test opening restrictions in a separate viewer. Avoid reusing the public sample passwords, and remember that visible signature images do not authenticate the file.

Limits and recovery

A password is unknown or the source is damaged
Ask the authorised sender for the password or a fresh export. The unlock tool is not a password-recovery service, and a successful viewer preview does not establish that the editor can process the file.
The task requires certified sanitisation or signature validity
Use a workflow approved for that requirement. These tools do not certify complete hidden-data removal, audit malware, validate signer identity or guarantee preservation of existing digital signatures after modification.

Samples and supporting references